Masatoshi Miyahara

Diagnostic Accuracy of 1.5-T Unenhanced Whole-Heart Coronary MR Angiography Performed with 32-Channel Cardiac Coils: Initial Single-Center Experience

PURPOSE To compare the imaging time and image quality obtained with whole-heart coronary magnetic resonance (MR) angiography performed with five- and 32-channel coils in healthy subjects and determine the accuracy of MR angiography performed with 32-channel coils in the detection of obstructive coronary artery disease (CAD). MATERIALS AND METHODS The institutional review board approved the study protocol, and all participants provided written informed consent. The authors studied 10 healthy subjects and 67 patients suspected of having CAD who were scheduled for coronary angiography. Unenhanced 1.5-T coronary MR angiography was performed with five- and 32-channel coils in healthy subjects and with 32-channel coils in patients. Clinically significant CAD was defined as a diameter reduction of at least 50% at coronary angiography. The sensitivity and specificity of coronary MR angiography were calculated. RESULTS The mean imaging time was substantially reduced from 12.3 minutes ± 4.2 (standard deviation) with five-channel coils to 6.3 minutes ± 2.2 with 32-channel coils, with equivalent image quality scores. Acquisition of MR angiograms was completed in all 67 patients, with a mean imaging time of 6.2 minutes ± 2.8. The prevalence of CAD in the study population was 58% (39 of the 67 patients). The areas under the receiver operating characteristic curves as determined at vessel- and patient-based analyses were 0.91 and 0.90, respectively; the sensitivity and specificity at vessel-based analysis were 86% and 93%, respectively. CONCLUSION Whole-heart coronary MR angiography performed at 1.5 T with 32-channel coils permits noninvasive detection of CAD with substantially reduced imaging time. This noninvasive approach can be an alternative to multidetector computed tomographic coronary angiography for ruling out obstructive CAD in patients who have a contraindication to contrast material and in young subjects who are at higher risk from ionizing radiation. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101323/-/DC1.

Isoenzymes of cyclic nucleotide phosphodiesterase in the human aorta : characterization and the effects of E4021

In extracts of the human aorta, five isoenzymes of cyclic nucleotide phosphodiesterase, namely, phosphodiesterase I, phosphodiesterase II, phosphodiesterase III, phosphodiesterase IV and phosphodiesterase V, were identified exclusively in the cytosolic fraction, and no phosphodiesterase activity was detected in the particulate fraction. Phosphodiesterase V and phosphodiesterase I were the major cGMP-hydrolyzing enzymes in the human aorta. A novel vasorelaxant, sodium 1-[6-chloro-4-(3,4-methylenedioxybenzyl)aminoquinazolin-2-yl ]piperidine-4- carboxylate sesquihydrate (E4021), relaxed prostaglandin F2 alpha-precontracted strips of human pulmonary artery with an ED50 value of 0.5 microM. E4021 potently and highly selectively inhibited the activity of phosphodiesterase V from human aorta with a Ki value of 2.4 nM. These results suggest that there is a unique distribution of phosphodiesterase isoenzymes in the human aorta and that inhibitors of phosphodiesterase V might be useful as a new type of vasodilator in the treatment of clinical disorders.

Characterization of the isoenzymes of cyclic nucleotide phosphodiesterase in human platelets and the effects of E4021.

In extracts of human platelets, three isoenzymes of cyclic nucleotide phosphodiesterase (PDE), namely, PDE2, PDE3, and PDE5, were identified; activities of PDE1 and PDE4 were not detected. In human platelets, the cGMP-hydrolytic activity was about six times higher than the cAMP-hydrolytic activity, and PDE5 and PDE3 are the major phosphodiesterase isoenzymes that hydrolyze cGMP and cAMP, respectively. PDE5 exhibited organ-specific expression in humans, and platelets were among the tissues richest in PDE5. A novel inhibitor of PDE5, sodium 1-[6-chloro-4-(3,4-methylenedioxybenzyl)aminoquinazolin-2-yl ] piperidine-4-carboxylate sesquihydrate (E4021), was a potent and highly selective inhibitor of human platelet PDE5. However, E4021 (up to 10 microM) did not inhibit 9,11-epithio-11,12-methano-thromboxane A2-induced platelet aggregation, in vitro. E4021 plus SIN-1 (3-morpholino-sydnonimine), at concentrations that had little effect individually, inhibited aggregation. These results suggest the unique distribution of phosphodiesterase isoenzymes in human platelets and the PDE5 inhibitors might be useful as a new class of antiplatelet drugs.

Effect of combination therapy of ezetimibe and rosuvastatin on regression of coronary atherosclerosis in patients with coronary artery disease.

Ezetimibe has been reported to provide significant incremental reduction in low-density-lipoprotein cholesterol (LDL-C) when added to a statin; however, its effect on coronary atherosclerosis has not yet been evaluated in detail. The aim of this study was to investigate the add-on effect of ezetimibe to a statin on coronary atherosclerosis evaluated by intravascular ultrasound (IVUS).In this prospective randomized open-label study, a total of 51 patients with stable coronary artery disease (CAD) requiring percutaneous coronary intervention (PCI) were enrolled, and assigned to a combination group (n = 26, rosuvastatin 5 mg/day + ezetimibe 10 mg/day) or a monotherapy group (n = 25, rosuvastatin 5 mg/day). Volumetric IVUS analyses were performed at baseline and 6 months after the treatment for a non-PCI site. LDL-C level was significantly reduced in the combination group (-55.8%) versus that in the monotherapy group (-36.8%; P = 0.004). The percent change in plaque volume (PV), the primary endpoint, appeared to decrease more effectively in the combination group compared with the monotherapy group (-13.2% versus -3.1%, respectively, P = 0.050). Moreover, there was a significant group × time interaction in the effects of the two treatments on PV (P = 0.021), indicating the regressive effect of the combination therapy on PV was greater than that of monotherapy for subtly different values of baseline PV in the two treatment groups. Moreover, percent change in PV showed positive correlations with percent change of LDL-C (r = 0.384, P = 0.015).Intensive lipid-lowering therapy with ezetimibe added to usual-dose statin may provide significant incremental reduction in coronary plaques compared with usual-dose statin monotherapy.

Biventricular pacing worsened dyssynchrony in heart failure patient with right-bundle branch block

The use of a biventricular pacing system for patients with complete right-bundle branch block (CRBBB) is still controversial. Although cardiac resynchronization therapy-defibrillator (CRT-D) was implanted in a heart failure patient with CRBBB, dyssynchrony worsened and stroke volume decreased, and this patient was re-admitted due to exacerbated heart failure. Therefore, evaluation of dyssynchrony and cardiac function after implantation of a biventricular pacing system may be needed in patients with atypical indications for CRT.

Efficacy of linear block at the left atrial roof in atrial fibrillation.

BACKGROUND After extensive encircling of ipsilateral pulmonary vein isolation (EEPVI) for atrial fibrillation (AF), we sometimes observe AF recurrence, or the occurrence of atrial tachycardia originating from the left atrium. This study examined the efficacy of additional linear ablation at the left atrial (LA) roof in combination with EEPVI to prevent arrhythmia recurrences. METHODS This study included 104 patients with drug-refractory AF (75 with paroxysmal, 29 with persistent). The patients in Group A (n=70) underwent EEPVI treatment alone, and the patients in Group B (n=34) underwent linear ablation at the LA roof in addition to EEPVI treatment. At 1, 3, 6, and 12 months after ablation, patients underwent clinical review and 24-h ambulatory electrocardiogram monitoring to identify asymptomatic arrhythmias. Follow-up included daily trans-telephonic event monitoring, transmitted irrespective of the patients symptoms. RESULTS At 12 months, 57% of Group A and 79% of Group B were free of arrhythmias (p<0.05). Cox regression analysis demonstrated that among the variables of age, sex, duration of AF, types of AF (paroxysmal or persistent), LA size, ejection fraction, existence of hypertension, ischemic heart disease, valvular heart disease, history of stroke, and the ablation technique, only the ablation technique of the linear block at the LA roof was the independent predictor of arrhythmia-free recovery after ablation. CONCLUSIONS EEPVI in combination with the linear ablation at the LA roof is associated with an improved clinical outcome compared with EEPVI alone.

New coronary aneurysm formation and malapposition after zotarolimus-eluting stent implantation in Kawasaki disease

Coronary artery involvement is the most important complication of Kawasaki disease. Coronary artery bypass surgery has been performed for ischemic heart disease caused by Kawasaki disease, however, long-term coronary graft patency is not satisfactory. Therefore, percutaneous coronary intervention (PCI) has its role in Kawasaki disease-related coronary artery disease. The incidence of new aneurysm is lower following stent implantation than balloon dilatation alone, even if a higher balloon pressure is applied. However, there are few reports about the efficacy of drug-eluting stent implantation for Kawasaki disease with coronary artery disease. Here, we describe a case of new coronary aneurysm formation and malapposition after zotarolimus-eluting stent implantation in Kawasaki disease. <Learning objective: New aneurysm formation after balloon angioplasty for coronary artery lesions in Kawasaki disease is a relatively well-known phenomenon, however there have been no reports about the influence of drug-eluting stents for coronary artery disease with Kawasaki disease. This report is useful when we consider strategies of revascularization for coronary artery disease with Kawasaki disease.>.

A case of aortic thrombosis and embolism preceding the progression of early esophageal cancer

Aortic thrombosis is rare, especially in non-atherosclerotic aortae. A 51-year-old woman presented with intermittent claudication in the right lower extremity. She was diagnosed as having peripheral artery disease on ultrasound. A computed tomography scan showed a large, sessile, aortic mural thrombus from the infrarenal abdominal aorta to the right common iliac artery. An arteriogram showed an abrupt occlusion of the right superficial femoral artery with collateral arteries. She had no risk factors for atherosclerosis. Interestingly, this occurred before early esophageal cancer progressed. Heparin was administered intravenously and later changed to warfarin. In the follow-up period, the thrombus disappeared, and her symptoms improved. A careful investigation for malignant disease is needed when aortic thrombus occurs in patients with no atherosclerosis risk factors. <Learning objective: Aortic thrombosis is rare, especially in non-atherosclerotic aortae. A patient who presented with descending aortic thrombosis and peripheral embolism complicating early esophageal carcinoma is presented. Interestingly, this occurred before the cancer progressed. A careful investigation for malignant disease is needed when aortic thrombus occurs in patients with no atherosclerosis risk factors.>.

Smooth Muscle Myosin Phosphatase

The endogenous phosphatase of chicken gizzard actomyosin contains two subunits of 58 and 38kDa, respectively, as we showed previously. This phosphatase was active with both isolated myosin light chain and intact myosin that had been phosphorylated by myosin light chain kinase as substrates, suggesting that phosphorylated myosin might be a substrate in situ. The 38-kDa subunit was identified as a catalytic subunit of a type lδ protein phosphatase (PP1δc), and the 58-kDa subunit was revealed to play a regulatory role in the binding of myosin. Studies with a monoclonal antibody (MoAb) to the 58-kDa subunit revealed that the 58-kDa protein was a product of proteolytic degradation of a protein of 130–133 kDa. The distribution of the 130-kDa component in chicken tissues was examined with the MoAb. An immunoreactive band of appropriate mobility was detected in analyses of all tissues except liver and skeletal muscle, and higher concentrations of the 130-kDa component were found in samples of smooth muscle. Intact myosin phosphatase was purified from chicken gizzard with the MoAb as probe. The purified holoenzyme was a heterotrimer that consisted of PP1bc (38kDa) and regulatory subunits of 130/133 kDa and 20 kDa. cDNA clones encoding the 130/133-kDa subunits were isolated from chicken gizzard cDNA libraries. The isolation of overlapping clones suggested the presence of the two isoforms. There were open reading frames of 2889 and 3012 bases that encoded proteins of 963 and 1004 amino acids with masses of 106.7 and 111.6 kDa, respectively. The deduced sequence of the larger isoform was 123 nucleotides longer in its central coding region than the other isoform. The characteristic N-terminal region was almost entirely composed of eight tandem repeats of 33 amino acids, which have been called the cdcl0/SWI6, or ankyrin, repeat. The 58-kDa fragment with the ability to bind to both myosin and the catalytic subunit was revealed to be located in the N-terminal half of the molecule. A cDNA clone (1338 bp) encoding chicken gizzard PPlδc was also isolated and sequenced. This clone contained an open reading frame that encoded a protein of 327 amino acids with a calculated molecular mass of 37kDa. Its amino acid sequence was identical to the analogous isoform from rats. These results suggest that smooth muscle myosin phosphatase is a novel holoenzyme composed of a type 1δ protein phosphatase and unique regulatory subunits.

Marked improvement of renal failure and severe hypertension after renal artery stenting in the solitary functioning kidney

Atherosclerotic renal artery stenosis (ARAS) can cause resistant hypertension, progressive renal failure and/or cardiorenal syndrome. Although no randomized study to demonstrate the superiority of renal stenting over medical treatment is available, a case-sensitive approach is required for the treatment of ARAS. Here, we describe a case report of a symptomatic ARAS patient with a solitary functioning kidney in which successful detection of ARAS by ultrasonography examination with the Doppler method and timely renal artery stenting were performed. <Learning objective: The clinical efficacy of renal artery stenting for symptomatic ARAS as a method of lowering blood pressure and preventing deterioration in renal function remains unproven. However, renal artery stenting performed based on enough investigation of clinical course and information by ultrasonography examination with Doppler method results in benefit to the patient with ARAS.>.